Modern vehicles have many interior and exterior components that, over the life of the vehicle, can produce squeaks, rattles, and other annoying sounds. Not surprisingly, vehicle rattles and noise-related complaints are very common at service centers. To achieve high customer satisfaction, automobile manufacturers seek to prevent squeaks, rattles, and other undesirable noises. However, this is not a simple task, since these noises can have a variety of sources, such as loose fasteners or surfaces moving relative to each other. These noises can be difficult and time consuming to locate, since they only appear when the vehicle is in use.
One method for locating a noise involves test-driving the vehicle by a trained mechanic. Often, a second mechanic must ride along in the vehicle to help locate the noise source. To increase the likelihood of locating the noise source, heating and air conditioning systems are turned off and windows are closed to reduce ambient noise levels. These situations can cause extreme discomfort to the automotive mechanics in freezing winter weather or extremely hot summer weather. Also, it can be unsafe for mechanics to operate the vehicle while their attention is focused on locating the noise. This approach is also harmful to the vehicle, since the mechanic often searches for uneven and rough roads to improve the likelihood of reproducing the noise, and striking potholes and bumps at significant speeds can cause misalignment of the wheels and worse. With this method, it can take several trips simply to locate the noise. Once the noise is located, the mechanic must disassemble the dash, door panel or console and continue to drive the vehicle while attempting to tighten, insulate or isolate the problem area. This method can be very time consuming and impractical.
As an alternative to test driving the vehicle, systems have been developed that allow the vehicle to remain stationary while the noise is located. But these systems have many disadvantages. They are often large and occupy considerable floor space and must be securely mounted to the floor. They can be costly to manufacture, purchase and transport, and the cost of transporting the machines can adversely affect their resale. In addition, they are complex and require specialized training to operate.
Some of these systems require the user to position the vehicle on a machine that functions like a chassis dynamometer. In one example, the tires rest against a roller assembly driven by an electromechanical drivetrain that is electrically powered. Each roller in the assembly can individually rotate around its center axis as the assembly itself rotates over a specific RPM range causing the longitudinal side of each roller to continuously strike the tires' treaded lower half at a predetermined position. This position is primarily a function of the tire size and the roller assembly's diameter and mounting position in the detection system. As the rollers continuously strike the tire, vibrations and shock waves are produced in the vehicle causing the same annoying rattles, squeaks and noises that are noticeable during driving conditions. A trained operator is required to locate the problem, repair it, and determine if the repair was successful. Rollers assemblies can be hazardous to the operator, since they include numerous moving parts that exert substantial forces and have minimal shielding. These systems can also cause damage to the vehicle. For instance, damage can occur to an automatic transmission where a front pump responsible for circulating transmission fluid is powered by the engine crankshaft, and in a hybrid vehicle, where overcharging of a battery pack or damage to an inverter can occur.